Optimization of Chemical Structure of Compatibilizers Based on Liquid Crystalline Diblock Copolymers for Reconciliation Between Inorganic Quantum Dots and Organic Cholesteric Liquid Crystals

Abstract

One of the key challenge of designing hybrid liquid crystalline (LC) materials is to combine organic and inorganic constituents in one stable system. To overcome this challenge, specially designed substances called compatibilizers may be used but the chemical structure of these substances and their content in the system should be adjusted properly. In this work, we optimized the chemical structure and the weight fraction of a compatibilzer between CdSe/ZnS quantum dots (QDs) and low molecular weight cholesteric liquid crystalline (CLC) matrix. As compatibilizers we used LC diblock copolymers containing a mesogenic block consisting of phenyl benzoate monomer units and poly(vinylpyridine) block of different polymerization degree, which is capable of binding to the surface of various nanoparticles. Using polarized optical microscopy and absorbance spectroscopy we found that the polymerization degree of poly(vinylpyridine) block can exert the influence on the CLC matrix properties such as a photonic band gap width and light scattering. The obtained results allowed us to prepare the hybrid CLC materials, which combine the high loading of QDs and unique optical properties of the cholestric phase. Our approach to creation hybrid CLC materials might be employed as a "flexible template" for the design of many other hybrid LC systems.